The enormous Owl Butterfly, also called the Giant Owl and, less usually, the Cocoa Mort Bleu, has a brown underside with false "eye" spots to deter predators.
With wings spread open it mimics an owl's face. There are some 20 similar-looking but different species, all native to forests of Central and South America.
The genus name Caligo comes from the calico brown colouring.

The two most encountered species in Butterfly Houses are the Giant Forest Owl, Caligo eurilochus above left, and the (Giant) Pale Owl,
Caligo memnon above right, both from Central America. The Owl Butterfly rarely opens its wings when at rest and, unfortunately, the main variation
in the species is on the topside. However, the Pale Owl shows a much lighter forewing when closed.

The topside has iridescent blue or mauve colouring. Left is that of the Giant Forest Owl, which is mainly mid-blue; above right is the Pale Owl.
Individuals vary and lose colour with age.

The Giant Forest Owl's darker forewing. It often has a wider white "iris" round the "pupil" on the eyespot, but not always.